When I started to work with my Texstudio 2.11.2 installation (windows 10), the equation preview facility of the editor worked. Now all of a sudden it doesn't any more. I have no idea what made it stop. I can't find any activation/deactivation field for this facility in the texstudio configuration, either. Instead of showing the equation preview, I now get a helpscreen ("16 math formulas ...") when hovering the cursor over the e.g. begin{equation}. The preview does not work any more even if I use the simplest file with no \usepackages. I tried reinstallation of Texstudio after deleting everything, including the .ini file, but it does not work any more. :-(